ABSTRACT
Toxicity is a measure of the degree to which a substance can be poisonous or harmful. It deals with the effects of chemical substances on organisms. The contamination of aquatic environment with various kinds of petroleum products has been a long-term issue and can as such affect the roles of microorganisms in food chain and as agents of degradation of substances in the aquatic environment. The acute toxicity of petroleum products was assessed on some bacterial species. The petroleum products used include; (drilling fluid – Oil based drilling fluids (OBDF) and Water based drilling fluids (WBDF), degreasers – Aquabreak and Rigwash, Oil Spill dispersants – OSD seacare and Industrial detergents- Gamazyne Biological Toilet Cleanser (BTC) and Teepol). The test bacteria were isolated and identified using standard methods. The test isolates used were Nitrobacter sp, Pseudomonas sp, Vibrio sp, Escherichia coli and Bacillus sp. The percentage log survival was used as an index for acute toxicity. The results obtained from the percentage log survival revealed a decrease in the percentage log survival as the concentrations and exposure periods increased for all the test isolates. The decrease in the survival of the test isolates suggested that the functions of each of the test isolate in the aquatic habitat may as well be impaired like degradation capability of Pseudomonas sp. The toxic effect of these chemicals could also affect the ability of the affected aquatic habitat in supporting life of aquatic organisms. The sensitivity trend for the test organisms at 95% confidence level showed a decreasing order; respectively. Nitrobacter species was responsible for the oxidation of nitrites to nitrates in the nitrogen cycle. The study revealed that these petroleum products were toxic to the test organisms. Growth inhibition of these microorganisms by the petroleum product may have led to the disruption of the biogeochemical cycles where they acted as the key degraders. Such could have had an overall effect on the entire biodegradation activities. The significance of the toxicity of the petroleum products on the test isolates was analyzed by ANOVA using SPSS and the result revealed that there was significant difference between the isolates and the hydrocarbons concentrations. For Nitrobacter species in freshwater, BTC had the lowest toxicity (LC50 2547.24 ppm) while WBDF and Aquabreak had the lowest toxicities (LC50 (454.02 ppm); (LC50 242.90 ppm) in marine and brackish water respectively. The higher the LC50, the lower the toxicity of the chemical. For Pseudomonas sp, OBDF had the lowest lethal toxicity (2073.69 ppm), WBDF (5776.69 ppm) and Aquabreak (230.04 ppm) in freshwater, marine and brackish water respectively. For Escherichia coli, WBDF had the lowest (2192.73 ppm) lethal toxicity on the isolate from freshwater, Aquabreak in marine water (1358.45 ppm) and brackish (4778.71 ppm). In Vibrio sp BTC had the lowest lethal toxicity LC50 in freshwater (2334.02 ppm), WBDF (1980.25 ppm) in marine water and Aquabreak (719.45 ppm) in brackish habitat. Same trend was also observed in Bacillus.
TABLE
OF CONTENTS
Title Page
i
Declaration
ii
Certification
iii
Dedication
iv
Acknowledgements
v
Table of Contents
vi
List of Tables
ix
List of Figures
x
Abstract
xii
CHAPTER 1 INTRODUCTION 1
1.1 Background
of the Study 1
1.2 Scope
of the Study
3
1.3 Statement
of the Problem
3
1.4 Aim
of the Study
4
1.5 Objectives
of the Study 4
1.6 Justification
of the Study 4
1.7 Significance
of the Study 5
CHAPTER 2
LITERATURE REVIEW 6
2.1
Nigeria's Petroleum Industry 7
2.2 Nigerian Oil Discovery
8
2.3
Nigerian Oil Production 9
2.4
Pollution caused by Oil as an issue
for the Environment 10
2.5 The
Upstream Industry
11
2.5 Downstream sector:
Refining, Processing and Marketing
12
2.6 Effect
of Petroleum Resources on Nigeria's Economy 13
2.7
Oil Industry's Environmental and
Health Effects 14
2.7.1
Drilling 17
2.7.2
Gas flaring
20
.2.7.3 Spilt oil
23
2.8 Petroleum
Products and Oil Industry's Upstream Sector 25
2.8.1 Fluids for drilling
25
2.8.2
Degreasers
28
2.8.3 Dispersants for oil spills
29
2.8.4
Detergents
36
2.9. Toxicology
of the Environment 37
2.9.1 Toxicology
of aquatic organisms 39
2.10 Toxicity of Fluids for Drilling
41
CHAPTER 3
MATERIALS AND METHODS 43
3.1 Sample Collection
43
3.2 Physicochemical
Analyses of the Water Sample 43
3.3 Bacterial
Isolation from the Water Samples 43
3.3.1 Isolation
of bacteria from the experimental water samples for ecotoxicity
tests
43
3.3.2 Characterization of
the test isolates
44
3.3.2.1 Colonial morphology
45
3.3.2.2 Microscopic examination
45
3.4 Organisms for
Ecotoxicity
45
3.5 Types and Sources of
Petroleum Products for Ecotoxicity Tests 45
3.6 Sterilization of
Materials
46
3.7 Preparation of Media
46
3.8 Ecotoxicity of Petroleum
Products on Nitrobacter spp and other
Bacterial
Isolates 57
3.8.1 Preparation of test
medium
57
3.8.2 Preparation of test
organisms
57
3.8.3 Preparation of standard bacterial
inoculum 57
3.8.4 Test procedure for the bacterial species 58
3.8.5 The percentage log survival of Nitrobacter spp and other bacterial
isolates in the
toxicants
58
3.9 Statistical Analysis
59
CHAPTER 4 RESULTS 60
4.1 Results
60
4.2 Discussion 113
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 121
5.1 Conclusion 121
5.2 Recommendations
121
5.3 Contributions to
Knowledge
122
References
LIST OF TABLES
4.1: Physicochemical
characteristics of the water samples 61
4.2: Colonial
characteristics of the bacterial isolates 62
4.3: Bacterial
isolates from the experimental aquatic environment 63
4.4: 24th
median lethal toxicity (PPM) on Nitrobacter 108
4.5: 24th
median lethal toxicity (PPM) on E.
coli
109
4.6: 24th
median lethal toxicity (PPM) on Pseudomonas
sp 110
4.7: 24th
median lethal toxicity (PPM) on Vibrio sp 111
4.8: 24th median lethal toxicity
(PPM) on Bacillus sp 112
LIST OF FIGURES
4.1 Lethal toxicity of the
oil based drilling fluid, water based drilling
fluid, BTC and
Teepol to Nitrobacter in fresh water
76
4.2: Lethal toxicity of Rigwash, Aquabreak and
OSD to Nitrobacter in
fresh water 77
4.3: Lethal toxicity
of the oil based drilling fluid, water based drilling fluid,
BTC and Teepol to Nitrobacter in marine water 78
4.4: Lethal toxicity of Rigwash, Aquabreak and
OSD to Nitrobacter in
marine
water
79
4.5: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Nitrobacter
in brackish water 80
4.6: Lethal toxicity of Rigwash, Aquabreak and
OSD to Nitrobacter in
brackish
water 81
4.7: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Pseudomonas sp in fresh water 82
4.8: Lethal toxicity of Rigwash, Aquabreak and
OSD to Pseudomonas
sp in fresh water 83
4.9: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Pseudomonas sp in marine water 84
4.10: Lethal toxicity of Rigwash, Aquabreak and OSD
to Pseudomonas sp
in marine water 85
4.11: Lethal toxicity of the Oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Pseudomonas
sp in brackish water 86
4.12: Lethal toxicity of Rigwash, Aquabreak and OSD
to Pseudomonas sp in
brackish water 87
4.13: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Vibrio
sp in fresh water 88
4.14: Lethal toxicity of Rigwash, Aquabreak and OSD
to Vibrio sp in
fresh water 89
4.15: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Vibrio
sp in marine water 90
4.16: Lethal toxicity of Rigwash, Aquabreak and OSD
to Vibrio sp in
marine water 91
4.17: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Vibrio sp in brackish water 92
4.18: Lethal toxicity of Rigwash, Aquabreak and OSD
to Vibrio sp in brackish
water 93
4.19: Lethal toxicity of the oil based drilling
fluid, water based drilling fluid,
BTC and Teepol to Escherichia coli sp in fresh water 94
4.20: Lethal toxicity of Rigwash, Aquabreak and OSD
to Escherichia coli sp
in fresh water 95
4.21: Lethal
toxicity of the oil based drilling fluid, water based drilling fluid,
BTC and Teepol to Escherichia coli sp in marine water 96
4.22: Lethal toxicity of Rigwash,
Aquabreak and OSD to Escherichia coli sp
in marine water 97
4.23: Lethal
toxicity of the oil based drilling fluid, water based drilling fluid,
BTC and Teepol to Escherichia coli sp in brackish water 98
4.24: Lethal
toxicity of Rigwash, Aquabreak and OSD to Escherichia coli sp in
brackish water 99
4.25: Lethal
toxicity of the oil based drilling fluid, water based drilling fluid,
BTC and Teepol to Bacillus sp in fresh water 100
4.26: Lethal
toxicity of Rigwash, Aquabreak and OSD to Bacillus sp in
fresh water 101
4.27: Lethal
toxicity of the oil based drilling fluid, water based drilling fluid,
BTC and Teepol to Bacillus sp in marine water 102
4.28: Lethal
toxicity of Rigwash, Aquabreak and OSD to Bacillus sp in marine
water 103
4.29: Lethal
toxicity of the oil based drilling fluid, water based drilling fluid,
BTC and Teepol to Bacillus sp in brackish water 104
4.30: Lethal
toxicity of Rigwash, Aquabreak and OSD to Bacillus sp in
brackish water 105
CHAPTER 1
INTRODUCTION
1.1
BACKGROUND OF THE STUDY
Hydrocarbon contamination caused by petrochemical
sector activities is currently one of the most serious environmental issues.
Accidental discharges of petroleum products are a major environmental problem (Nilanjana and Preethy, 2011).
Petroleum and petrochemical pollution have been identified as a big and
serious concern in the environment (Alexander, 2000). Because oil is so easily
absorbed into the food chain, most of its components are hazardous to humans
and wildlife. This has aroused a lot of concern over the effects of hydrocarbon
pollution of the environment (Alexander, 2000; Semple et al., 2003; Stroud et al.,
2007, 2009; Nrior and Odokuma, 2015a).
Drilling fluid (oil and water basis), Dispersants for oil
spills, degreasers, and industrial detergents are just a few of the petroleum
products used in Nigeria's upstream sector (EGASPIN, 2002).
They are a mixture of chemical
substances, both natural and synthetic that are used in cooling and greasing
the drill bit, removing cuttings from the bottom of the hole and bringing them
to the surface, controlling formation pressure, and improving the drill string
and equipment in the hole (Burke and Veil, 1995).
Drilling muds in Nigeria are divided into two
categories: Muds made of water and oil (mineral/synthetic or
pseudo-mineral/synthetic (EGASPIN, 2002). Drilling off-shore is becoming more common
as it is a means of discovering new oil reserves. This has become a new source
of petroleum pollution.
As a detergent and cleaning agent, any soap or
non-soap powder can be used in both industrial and home settings (Holding,
2005). The need for an improved method of biodegradation has become more
imperative owing to the introduction of new synthetic materials or products
into the aquatic environment. Again, the difficulty in the management of these
new synthetic products has led credence in continued call for the treatment of
these pollutants before they are discharged into the aquatic environments. Detergents are detrimental to the environment, they could
be instrumental to the breakdown of the exterior mucus layer that shields fish
from germs and other infections, severe damage to the gills, decreasing of the
water's surface tension, algae bloom that release toxins and restrict oxygen in
streams, and a decrease in the capacity of aquatic creatures to reproduce (Holding,
2005). The primary factors to the detergents' toxicity are the sodium silicate
solution and the surfactant employed in their formulations (Holding, 2005).
Humans use water sources for recreation, and some
aquatic habitats are critical to the tourism sector, particularly in temperate
areas (Fuhrman, 1991).
Most Nigerian chemical, culinary, agricultural,
and petroleum-based industries dump their wastes in natural surface waters,
which include ponds, streams, rivers, estuaries, lagoons, lakes, seas, and
oceans, either directly or indirectly (NEST, 1991; Nrior and Wosa, 2016). These
wastes are capable of causing harm to aquatic microbial species. Therefore, the
research study was to investigate the toxic effects of some petroleum products
used in the upstream sector of the petroleum industry for oil exploration and
production activities.
1.2 SCOPE OF THE STUDY
The scope of the study included:
i.
The determination of the effect of acute
toxicity of petroleum compounds like drilling fluids, oil dispersants,
degreasers, and industrial detergents on microbial species isolated from the aquatic
ecosystems.
ii.
The evaluation of physicochemical
properties of the experimental marine, brackish, and freshwater
ecosystems.
iii.
Isolation and identification of
bacterial species associated with the experimental marine, brackish, and
freshwater ecosystems.
1.2
STATEMENT OF THE PROBLEM
i.
Increases in carbon dioxide and
other gases are directly linked to the usage of fossil fuel sources in energy
production. Such increase in carbondioxide content of the air has led to the
current global warming trend (Nrior et
al., 2017b).
ii.
Petroleum exploration, development,
and production have negative and severe local effects on the aerial, soil and aquatic
environments. (Aniefiok, 2013).
iii.
The vast amounts of offshore oil and
gas exploration, as well as the scarcity of data on the impact of waste on
aquatic ecosystems, have put existing petroleum sector management rules and recommendations to the test (Aslan et al., 2019). In view of this, it has
become imperative to determine the influence of petroleum compounds on aquatic
lives more especially in the Niger Delta Area of Nigeria.
1.4 AIM
OF THE STUDY
This study was aimed at finding out the ecotoxicological
effects of various petroleum products on aquatic bacterial species.
1.5 OBJECTIVES OF THE STUDY
The specific
objectives of the study included;
i.
The isolation and characterization
of species of bacteria associated with selected aquatic habitats (Marine,
Freshwater and Brackish) in the Niger Delta Area of Nigeria.
ii.
The selection of test bacterial
species from the array of the bacterial isolates for more detailed study in terms of the effect
of some petroleum products and detergents on the
activities of the said bacteria on the study aquatic environment.
iii.
The said products included; drilling
fluids, oil dispersants, degreasers, and industrial detergents.
1.6
JUSTIFICATION OF THE STUDY
i.
The assessment of organic chemical
toxicity is a necessary component of environmental risk assessment and this is
required by law. (European Parliament Regulation (EC), 2004).
ii.
There is scanty information on the petroleum products employed in Nigeria's petroleum
industry which have ecotoxicological effects on aquatic organisms. In view of
this, there is urgent need to provide baseline data on the effects of drilling
fluids, oil dispersants,
degreasers, and industrial detergents that are commonly employed in crude oil
exploration on various aquatic species especially aquatic bacterial
populations.
1.7 SIGNIFICANCE OF THE STUDY
The
significance of the research study included the following:
i.
Till date the effects or toxicity of
drilling fluids, oil dispersants, degreasers, and industrial detergents on
aquatic bacterial species of the aquatic environments within the crude oil
exploiting areas of the Niger Delta are yet to be determined.
ii.
It has also become imperative to determine
the LC50 for each product used in the petroleum exploitation
industry.
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